The present invention disclosed herein relates to an active metamaterial device and a manufacturing method of the same, and more particularly, to an active metamaterial device in which graphene is applied and a manufacturing method of the same.
A metamaterial may include an artificial material in which artificial structures are periodically arranged instead of atoms and molecules. The structures inside the metamaterial may be much bigger than molecules. Thus, the path in which an electromagnetic wave passing through the metamaterial progresses may be interpreted by macroscopic Maxwell equations. On the other hand, the structures inside the metamaterial may have a size much smaller than an working electromagnetic wavelength. Therefore, the metamaterial may include structures of shapes and sizes in which macroscopic material response characteristics can be created from the electromagnetic responses of an array of the designed patterns. The metamaterial is formed of a typical material such as a conductor or semiconductor, and its collective characteristics are changed by arranging it in extremely small repetitive patterns. Therefore, the metamaterial may control electromagnetic waves in a manner not possible with a general material.
A typical technique for actively controlling the characteristics of a metamaterial includes a method of changing the properties of a base material of the metamaterial by applying a direct current (DC) electric field to the metamaterial. In this method, a metamaterial is first designed on a semiconducting base material through a metal pattern and metamaterial unit cells connected to one electrode so as to effectively form Schottky diodes around the metamaterial unit cells when a DC bias voltage is applied from outside. When a DC voltage is applied to the metamaterial metal pattern through an ohmic contact region, a charge depletion region is formed near the metamaterial unit cell. As a result, the electrical conductivity of the semiconducting base material contacting the metamaterial is changed, optical properties such as the transmittance/refractive index of the metamaterial are changed accordingly, and the foregoing is applied to a metamaterial switching device or phase modulator. In addition to the foregoing method, a metamaterial has been developed, in which the overall metamaterial properties are controlled by changing the metamaterial's base material properties through the use of electrical or thermal phase transition. A phase transition type device has the disadvantage of a slow operating speed.